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A general term for the layer or mantle of fragmental and unconsolidated rock material that nearly everywhere forms the surface of land and overlies or covers bedrock. It includes alluvium, colluvium, residuum, debris, earth, and soil.

Residual Soil

An unconsolidated or partly-weathered, parent material soil that developed in place by the physical and chemical weathering from the consolidated rock on which it lies.


A long, narrow continental trough that is bounded by normal faults. It marks a zone along which the entire thickness of the lithosphere has ruptured under extension.


Rock or other material used to armor shorelines, streambeds, bridge abutments, pilings, and other shoreline structures against scour, water, or ice erosion.


The area of land adjacent to a waterway.


Of, like, relating to, or produced by a river.


An aggregate of one or more minerals, or a body of undifferentiated mineral matter.

Rock Fall

A type of slope movement in which a single mass of rock of any size is detached from a steep slope or cliff along a surface on which little or no shear displacement occurs. The detached material descends mostly through the air by free fall, bounding, or rolling.

Rock Slide

A slope movement initiated by slippage along a well-defined failure surface that is usually planar or curvi-planar, in which the displaced mass is composed of rock that was intact and in its natural place before the initiation of movement.